Second equation of electrostatic coupling
The voltage
across an electrostatic transducer is the sum of a DC component
and an AC component u(t) :
.
The electrical charge
of an electrostatic transducer is therefore written,
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By neglecting the second order terms:
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By conserving only the AC component of this equation, and observing that the current i is the temporal derivative of the charge Q,
and that the velocity
of the membrane is the temporal derivative of the displacement
, the temporal derivative of the coupling equation is written
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In the harmonic domain
, this equation is written
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where
is the electrostatic coupling factor
